Clutch torque estimating method for vehicle transmission

ABSTRACT

A clutch torque estimating method for a transmission of a vehicle may include inputting model engine torque to a powertrain model by a controller; inputting target clutch torque of a first clutch and target clutch torque of a second clutch to the powertrain model by the controller; inputting shifting information related to the vehicle to the powertrain model by the controller; correcting the powertrain model in real time by feeding back an engine angular velocity error, a clutch angular velocity error of the first clutch, a clutch angular velocity error of the second clutch, a wheel angular velocity error to the powertrain model by the controller; and estimating clutch torque of the first clutch and clutch torque of the second clutch by determining the powertrain model by the controller.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2019-0033851, filed Mar. 25, 2019, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a transmission clutch, particularly, toa technology of estimating torque which is transmitted through a dryclutch of a Dual Clutch Transmission (DCT).

Description of Related Art

In a dual-clutch transmission (DCT) using a dry clutch, controllercontrols the clutch to generate a clutch actuator stroke correspondingto desired clutch torque while managing the relationship between thestroke of the clutch actuator and the clutch torque through aTorque-Stroke (T-S) curve.

However, the characteristics of the dry clutch continuously change dueto the temperature of the clutch, a wear state, deformation of portionsrelated to the clutch, etc. while a vehicle is driven, so that the T-Scurve continuously changes as time passes, and it is difficult todirectly measure clutch torque through a sensor. Accordingly, there is ademand for a technology that can estimate as accurately as possible thevalue of the current clutch torque.

A technology that estimates clutch torque using an observer of controlengineering in the related art has been provided, but a more accurateestimate of clutch torque is necessary to improve launch performance andshifting quality of vehicles.

The information included in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and may not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing aclutch torque estimating method for a transmission of a vehicle, themethod being able to further improve launch performance and shiftingquality of a vehicle by more accurately estimating clutch torque of adry clutch which is used for a DCT, being able to improve the commercialvalue of the vehicle.

In view of the above aspect, a clutch torque estimating method for atransmission of a vehicle of the present invention may include:inputting model engine torque to a powertrain model by a controller;inputting target clutch torque of a first clutch and target clutchtorque of a second clutch to the powertrain model by the controller;inputting shifting information related to the vehicle to the powertrainmodel by the controller; correcting the powertrain model in real time byfeeding back an engine angular velocity error which is the differencebetween a measured engine angular velocity and an estimated engineangular velocity determined from the powertrain model, a clutch angularvelocity error of the first clutch which is the difference between ameasured clutch angular velocity of the first clutch and an estimatedclutch angular velocity of the first clutch determined from thepowertrain model, a clutch angular velocity error of the second clutchwhich is the difference between a measured clutch angular velocity ofthe second clutch and an estimated clutch angular velocity of the secondclutch determined from the powertrain model, and a wheel angularvelocity error which is the difference between a measured wheel angularvelocity and an estimated wheel angular velocity determined from thepowertrain model, to the powertrain model by the controller; estimatingclutch torque of the first clutch and clutch torque of the second clutchby determining the powertrain model by the controller; and controllingthe first clutch and the second clutch using the estimated clutch torqueof the first clutch and the estimated clutch torque of the second clutchby the controller.

The powertrain model may include an engine model determined according toengine dynamics; a first clutch model and a second clutch modeldetermined according to clutch dynamics; and a vehicle model determinedaccording to vehicle dynamics.

The model engine torque may be input to the powertrain model togetherwith an estimated engine torque error determined bycumulative-integrating the engine angular speed error.

The target clutch torque of the first clutch may be multiplied by aclutch characteristic variable of the first clutch determined by aclutch friction force characteristic model of the first clutch and isthen input to the powertrain model, and the target clutch torque of thesecond clutch may be multiplied by a clutch characteristic variable ofthe second clutch determined by a clutch friction force characteristicmodel of the second clutch and is then input to the powertrain model.

The engine model may be

J _(e){circumflex over ({dot over (ω)})}_(e) =T _(e0)+{circumflex over(δ)}_(e)−{circumflex over (μ)}_(c1) T _(tc1)−{circumflex over (μ)}_(c2)T _(tc2), where

J_(e): Engine moment of inertia

{circumflex over ({dot over (ω)})}_(e): Estimated engine angularacceleration

T_(e0): Model engine torque

{circumflex over (δ)}_(e): Estimated engine torque error

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch.

The first clutch model may be

${{J_{c\; 1}^{\prime}{\overset{.}{\hat{\omega}}}_{c\; 1}} = {{{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} + {\frac{\gamma_{T}\left( \phi_{e} \right)}{\gamma_{T}\left( \phi_{o} \right)}{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} - \frac{T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{o} \right)}}},$

where

J′_(c1): Equivalent moment of inertia of first clutch

{circumflex over ({dot over (ω)})}_(c1): Estimated clutch angularacceleration of first clutch

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch.

φ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . )

φ_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . )

γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e)

γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o)

{circumflex over (ω)}_(w): Estimated wheel angular velocity

T_(so)({circumflex over (ω)}_(c1),{circumflex over (ω)}_(w)): Torsionaltorque of driveshaft when odd-numbered gear stage is engaged

${T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}\mspace{11mu} d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}}$

k_(s): Stiffness coefficient of driveshaft

b_(s): Damping coefficient of driveshaft

{circumflex over (ω)}₁: Estimated clutch angular velocity of firstclutch.

The second clutch model may be

${{J_{c\; 2}^{\prime}{\overset{.}{\hat{\omega}}}_{c\; 2}} = {{{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} + {\frac{\gamma_{T}\left( \phi_{o} \right)}{\gamma_{T}\left( \phi_{e} \right)}{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} - \frac{T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{e} \right)}}},$

where

J′_(c2): Equivalent moment of inertia of second clutch

{circumflex over ({dot over (ω)})}_(c2): Estimated clutch angularacceleration of second clutch

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch

φ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . )

φ_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . )

γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e)

γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o).

{circumflex over (ω)}_(w): Estimated wheel angular velocity

T_(se)({circumflex over (ω)}_(c2),{circumflex over (ω)}_(w)): Torsionaltorque of driveshaft when even-numbered gear stage is engaged

${T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}}$

k_(s): Stiffness coefficient of driveshaft

b_(s): Damping coefficient of driveshaft

{circumflex over (ω)}_(c2): Estimated clutch angular velocity of secondclutch.

The vehicle model may be

J _(v){circumflex over ({dot over (ω)})}_(w) =T _(sn)({circumflex over(ω)}_(ci),{circumflex over (ω)}_(w))−T _(L)({circumflex over (ω)}_(w)),where

J_(v): Equivalent moment of inertia of vehicle

{circumflex over ({dot over (ω)})}_(w): Estimated wheel angularacceleration

T_(sn)({circumflex over (ω)}_(ci),{circumflex over(ω)}_(w)):T_(so)({circumflex over (ω)}_(c1),{circumflex over (ω)}_(w))when an odd-numbered gear stage is engaged, T_(se)({circumflex over(ω)}_(c2),{circumflex over (ω)}_(w)) when an even-numbered gear stage isengaged

n=o or e, i=1 or 2

${T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}}$

T_(so): Torsional torque of driveshaft when odd-numbered gear stage isengaged

{circumflex over (ω)}_(c1): Estimated clutch angular velocity of firstclutch

{circumflex over (ω)}_(w): Estimated wheel angular velocity

k_(s): Stiffness coefficient of driveshaft

b_(s): Damping coefficient of driveshaft

ω_(c1): Measured clutch angular velocity of first clutch

ω_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . )

γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o)

${T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\overset{\hat{}}{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}}$

T_(se): Torsional torque of driveshaft when even-numbered gear stage isengaged

{circumflex over (ω)}_(c2): Estimated clutch angular velocity of secondclutch

ω_(c2): Measured clutch angular velocity of second clutch

φ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . )

γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e)

T_(L)({circumflex over (ω)}_(w)): Vehicle load.

The clutch friction force characteristic model of the first clutch maybe

{circumflex over (μ)}_(c1)({circumflex over (ω)}_(s1),{circumflex over(z)}_(c1))=σ_(c10) {circumflex over (z)} _(c1)+σ_(c11){circumflex over(ż)}_(c1)+σ_(c12){circumflex over (ω)}_(s1), where

{circumflex over (ω)}_(s1)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c1),

${{\overset{.}{\hat{z}}}_{c\; 1} = {{\hat{\omega}}_{s\; 1} - {\sigma_{c\; 10}\frac{{\hat{\omega}}_{s\; 1}}{g\left( {\hat{\omega}}_{s\; 1} \right)}{\hat{z}}_{c\; 1}}}},$

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

{circumflex over (ω)}_(s1): Estimated clutch slip of first clutch

{circumflex over (ω)}_(e): Estimated engine angular velocity

σ_(c1): Estimated clutch angular velocity of first clutch

σ_(c10): Stiffness coefficient against internal friction force of firstclutch

{circumflex over (ω)}_(c11): Damping coefficient against internalfriction force of first clutch

{circumflex over (ω)}_(c12): Damping coefficient for slip of firstclutch

z_(c1): Internal variable for determining friction force of first clutch

g({circumflex over (ω)}_(s1)): Friction force according to slip of firstclutch when a change of z_(c1) is 0 (normal state)

g({circumflex over (ω)}_(s1))=f _(c1c)+(f _(c1s) −f _(c1c))e^(−({circumflex over (ω)}) ^(s1) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²

f_(c1c): Coefficient of kinetic friction of first clutch

f_(c1s): Coefficient of static friction of first clutch

ω_(cs): Critical slip velocity (threshold velocity for discriminatingstatic friction and kinetic friction).

The clutch friction force characteristic model of the second clutch maybe

{circumflex over (μ)}_(c2)({circumflex over (ω)}_(s2),{circumflex over(z)}_(c2))=σ_(c20) {circumflex over (z)} _(c2)+σ_(c21){circumflex over(ż)}_(c1)+σ_(c12){circumflex over (ω)}_(s2), where

{circumflex over (ω)}_(s2)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c2)

${\overset{.}{\hat{z}}}_{c\; 2} = {{\hat{\omega}}_{s\; 2} - {\sigma_{c\; 20}\frac{{\hat{\omega}}_{s\; 2}}{g\left( {\hat{\omega}}_{s\; 2} \right)}{\hat{z}}_{c\; 2}}}$

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

{circumflex over (ω)}_(s2): Estimated clutch slip of second clutch

{circumflex over (ω)}_(e): Estimated engine angular velocity

{circumflex over (ω)}_(c2): Estimated clutch angular velocity of secondclutch

σ_(c20): Stiffness coefficient against internal friction force of secondclutch

σ_(c21): Damping coefficient against internal friction force of secondclutch

σ_(c22): Damping coefficient for slip of second clutch

z_(c2): Internal variable for determining friction force of secondclutch

g({circumflex over (ω)}_(s2)): Friction force according to slip ofsecond clutch when a change of z_(c2) is 0 (normal state)

g({circumflex over (ω)}_(s2))=f _(c2c)+(f _(c2s) −f _(c2c))e^(−({circumflex over (ω)}) ^(s1) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²

f_(c2c): Coefficient of kinetic friction of second clutch

f_(c2s): Coefficient of static friction of second clutch

ω_(cs): Critical slip velocity (threshold velocity for discriminatingstatic friction and kinetic friction).

The present invention makes it possible to further improve launchperformance and shifting quality of a vehicle by more accuratelyestimating clutch torque of a dry clutch which is used for a DCT, beingable to improve the commercial value of the vehicle.

Furthermore, according to an exemplary embodiment of the presentinvention, it is possible to estimate and find out clutch torque evenwithout a sensor for measuring clutch torque, so that the presentinvention may be used to compensate for or learn a T-S curve map of therelated art. Furthermore, it is possible to control clutches without aT-S curve map.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of a vehicle with adual-clutch transmission (DCT) to which an exemplary embodiment of thepresent invention may be applied;

FIG. 2 is a conceptual diagram illustrating a clutch torque estimatingmethod for a transmission of a vehicle according to an exemplaryembodiment of the present invention;

FIG. 3 is a graph illustrating the meaning of a clutch characteristicvariable;

FIG. 4 is a graph illustrating clutch torque which is estimated when avehicle is launched in accordance with various aspects of the presentinvention; and

FIG. 5 is a diagram expressing in detail a powertrain model of FIG. 2.

It may be understood that the appended drawings are not necessarily toscale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the present invention.The specific design features of the present invention as includedherein, including, for example, specific dimensions, orientations,locations, and shapes will be determined in part by the particularlyintended application and use environment.

In the figures, reference numbers refer to the same or equivalentportions of the present invention throughout the several figures of thedrawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the presentinvention(s) will be described in conjunction with exemplary embodimentsof the present invention, it will be understood that the presentdescription is not intended to limit the present invention(s) to thoseexemplary embodiments. On the other hand, the present invention(s)is/are intended to cover not only the exemplary embodiments of thepresent invention, but also various alternatives, modifications,equivalents and other embodiments, which may be included within thespirit and scope of the present invention as defined by the appendedclaims.

FIG. 1 is a diagram showing the configuration of a vehicle with a DCT towhich an exemplary embodiment of the present invention may be applied,in which power from an engine E is transmitted to a first input shaftIN1 and a second input shaft IN2 of a DCT through a first clutch CL1 anda second clutch CL2, respectively, and then supplied to driving wheels Wthrough an output OUT after shifting.

Furthermore, a clutch actuator CA1 of a first clutch and a clutchactuator CA2 of a second clutch are provided to drive the first clutchCL1 and the second clutch CL2, respectively, and a shifting actuator SAfor performing shifting using a selecting and shifting function isprovided. These actuators are controller by a controller CLR forautomatic shifting.

The controller CLR receives an accelerator pedal operation amount by adriver through an Accelerator Position Sensor (APS) 7, receivesinformation such as the engine velocity and torque, the vehiclevelocity, etc., and controls the clutch actuator CA1 of the firstclutch, the clutch actuator CA2 of the second clutch, and the shiftingactuator SA such that the dual-clutch transmission (DCT) automaticallyperforms shifting to be fitted to the driving situation of the vehicle.

For example, to achieve clutch torque of 50 Nm through the first clutch,the controller find out a clutch actuator stroke corresponding to 50 Nmfrom a T-S curve map provided in advance for the first clutch and thencontrols the clutch actuator to operate by the stroke, whereby the firstclutch is controlled to generate clutch torque of 50 Nm.

The engine is controlled by a separate Engine Management System (EMS)and the controller CLR can receive information related to the engine bycommunicating with the EMS.

For reference, the controller CLR described above may be a TransmissionManagement System (TMS), and in some cases, it may be an integratedcontrol system of the EMS and the TMS.

The DCT implements odd-numbered gear stages such as a 1-gear stage, a3-gear stage, and a 5-gear state of a series of gear stages andeven-numbered gear stages such as a 2-gear stage, a 4-gear stage, and a6-gear stage through different input shafts and clutches. For example,the first clutch and the first input shaft are designed to implement theodd-numbered gear stages, and the second clutch and the second inputshaft are designed to implement the even-numbered gear stages.Accordingly, when shifting is sequentially performed, for example, fromthe 3-gear stage to the 4-gear stage, the first clutch is disengaged andthe second clutch is engaged, preventing torque interruption andsecuring smooth shifting.

In shifting, the clutch which is disengaged such as the first clutch iscalled a disengaging clutch and the clutch which is engaged such as thesecond clutch is called an engaging clutch. Accordingly, the input shaftconnected to the disengaging clutch is also called a disengaging inputshaft and the input shaft connected to the engaging clutch is alsocalled an engaging input shaft.

Referring to FIG. 2, an exemplary embodiment of a clutch torqueestimating method for a transmission of a vehicle of the presentinvention include: inputting model engine torque to a powertrain modelby a controller (S10); inputting target clutch torque of a first clutchand target clutch torque of a second clutch to the powertrain model bythe controller (S20); inputting shifting information related to thevehicle to the powertrain model by the controller (S30); correcting thepowertrain model in real time by feeding back an engine angular velocityerror which is the difference between a measured engine angular velocityand an estimated engine angular velocity determined from the powertrainmodel, a clutch angular velocity error of the first clutch which is thedifference between a measured clutch angular velocity of the firstclutch and an estimated clutch angular velocity of the first clutchdetermined from the powertrain model, a clutch angular velocity error ofthe second clutch which is the difference between a measured clutchangular velocity of the second clutch and an estimated clutch angularvelocity of the second clutch determined from the powertrain model, anda wheel angular velocity error which is the difference between ameasured wheel angular velocity and an estimated wheel angular velocitydetermined from the powertrain model, to the powertrain model by thecontroller (S40); estimating clutch torque of the first clutch andclutch torque of the second clutch by determining the powertrain modelby the controller; and controlling the first clutch and the secondclutch using the estimated clutch torque of the first clutch and theestimated clutch torque of the second clutch by the controller.

The powertrain model may include an engine model determined according toengine dynamics; a first clutch model and a second clutch modeldetermined according to clutch dynamics; and a vehicle model determinedaccording to vehicle dynamics.

That is, various aspects of the present invention provide a powertrainmodel including the engine model, the first clutch model, the secondclutch model, and the vehicle model, inputting model engine torque,target clutch torque of the first clutch, target clutch torque of thesecond clutch, vehicle shifting information to the powertrain model,corrects the powertrain model in real time by feeding back an engineangular velocity error, a clutch angular velocity error of the firstclutch, a clutch angular velocity error of the second clutch, and awheel angular velocity error to the powertrain model, and estimateclutch torque of the first clutch and clutch torque of the second clutchfrom the powertrain.

When estimating the clutch torque of the first clutch and the clutchtorque of the second clutch, the present invention estimates the clutchtorque of the first clutch and the clutch torque of the second clutch onthe basis of more detailed and accurate information related to the stateof a vehicle by use of the powertrain model including the engine model,the first clutch model, the second clutch model, and the vehicle model.Accordingly, it is possible to more accurately estimate the clutchtorque of the clutches in a wider operation period. Therefore, launchperformance and shifting quality of a vehicle are improved, increasingthe commercial value of the vehicle.

For reference, the measured engine angular velocity may be measured by acrank angle sensor, the measured clutch angular velocity of the firstclutch may be measured by a sensor that measures the rotational velocityof the first input shaft connected to the first clutch, the measuredclutch angular velocity of the second clutch may be measured by a sensorthat measures the rotational velocity of the second input shaftconnected to the second clutch, and the measured wheel angular velocitymay be measured by a wheel velocity sensor mounted on a wheel of avehicle.

The model engine torque, which is provided from the EMS to thecontroller, means the fuel amount which is controlled by the EMS inaccordance with the vehicle state such as an APS signal according to theacceleration pedal operation state by a driver, and a torque which isexpected to be output from the engine in accordance with the ignitiontime.

That is, the model engine torque is not actual engine torque, but enginetorque determined from a map or a model of engine output torque for anengine control amount such as a fuel amount and ignition time by the EMSand transmitted to the controller through Controller Area Network (CAN)communication etc.

The model engine torque is configured to be input to the powertrainmodel together with an estimated engine torque error determined bycumulative-integrating the engine angular velocity error.

That is, there may be a difference between the model engine torque andthe actual engine torque, so that the difference is corrected by theestimated engine torque error to engine torque closer to the actualengine torque to the engine model of the powertrain model.

The estimated engine torque may be determined from the following Formula1.

{circumflex over (δ)}_(e)−∫₀ ^(t) l _(ei)(ω_(e)−{circumflex over(ω)}_(e))dτ  [Formula 1]

where,

{circumflex over (δ)}_(e): Estimated engine torque error

ω_(e): Measured engine angular velocity

{circumflex over (ω)}_(e): Estimated engine angular velocity

l_(ei): Feedback gain for engine angular velocity

The engine model forming the powertrain model may be expressed as thefollowing Formula 2.

J _(e){circumflex over ({dot over (ω)})}_(e) =T _(e0)+{circumflex over(δ)}_(e)−{circumflex over (μ)}_(c1) T _(tc1)−{circumflex over (μ)}_(c2)T _(tc2), where  [Formula 2]

J_(e): Engine moment of inertia

{circumflex over ({dot over (ω)})}_(e): Estimated engine angularacceleration

T_(e0): Model engine torque

{circumflex over (δ)}_(e): Estimated engine torque error

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch.

Real-time correction by feeding back the engine angular velocity errorto the engine model may be expressed as the following Formula 3.

J _(e){circumflex over ({dot over (ω)})}_(e) −T _(e0)+{circumflex over(δ)}_(e)−{circumflex over (μ)}_(c1) T _(tc1)−{circumflex over (μ)}_(c2)T _(tc2) +l _(e)(ω_(e)−{circumflex over (ω)}_(e))  [Formula 3]

where,

ω_(e): Measured engine angular velocity

{circumflex over (ω)}_(e): Estimated engine angular velocity

l_(e): Observer feedback gain for engine angular velocity error

ω_(e)−{circumflex over (ω)}_(e): Engine angular velocity error.

Under the theoretical assumption that a difference between the enginemodel and the actual engine dynamics has been reflected to a differencebetween the actually measured engine angular velocity and the estimatedengine angular velocity determined from a model, correction which isperformed by feeding back the engine angular velocity error to theengine model by the controller is based on that when the difference isrepeatedly multiplied by an appropriate observer feedback gain, thedifference gradually decreases and the engine model will be closer tothe actual engine dynamics.

For reference, the present invention estimates {circumflex over(μ)}_(c1)T_(tc1) which is the clutch torque of the first clutch and{circumflex over (μ)}^(c2)T_(tc2) which is the clutch torque of thesecond clutch in the above Formulae to use them for controlling thefirst clutch and the second clutch.

Using the estimated clutch torque of the first clutch and the estimatedclutch torque of the second clutch for controlling the first clutch andthe second clutch may mean ignoring the target clutch torque and usingthe estimated clutch torque, or comparing the target clutch torque andthe estimated clutch torque and using an intermediate value, when aproblem may be caused due to a large difference between the actualclutch torque and the target clutch torque output from the T-S curvemap, for example, in launching of a vehicle exemplified in FIG. 4.

The target clutch torque of the first clutch is multiplied by the clutchcharacteristic variable of the first clutch determined by a clutchfriction force characteristic model of the first clutch and is theninput to the powertrain model.

The target clutch torque of the second clutch is multiplied by theclutch characteristic variable of the second clutch determined by aclutch friction force characteristic model of the second clutch and isthen input to the powertrain model.

The first clutch model may be expressed as the following Formula 4.

$\begin{matrix}{{J_{c\; 1}^{\prime}{\overset{.}{\hat{\omega}}}_{c\; 1}} = {{{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} + {\frac{\gamma_{T}\left( \phi_{e} \right)}{\gamma_{T}\left( \phi_{o} \right)}{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} - \frac{T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{o} \right)}}} & {{Formula}\mspace{14mu} 4}\end{matrix}$

where

J′_(c1): Equivalent moment of inertia of first clutch

{circumflex over ({dot over (ω)})}_(c1): Estimated clutch angularacceleration of first clutch

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch

φ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . )

φ_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . )

γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e).

γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o)

{circumflex over (ω)}_(w): Estimated wheel angular velocity

T_(so)({circumflex over (ω)}_(c1),{circumflex over (ω)}_(w)): Torsionaltorque of driveshaft when odd-numbered gear stage is engaged

${T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}}$

k_(s): Stiffness coefficient of driveshaft

b_(s): Damping coefficient of driveshaft

{circumflex over (ω)}_(c1): Estimated clutch angular velocity of firstclutch.

Real-time correction by feeding back the clutch angular velocity errorof the first clutch to the first clutch model may be expressed as thefollowing Formula 5.

$\begin{matrix}{{J_{c\; 1}^{\prime}{\overset{\overset{\cdot}{\hat{}}}{\omega}}_{c\; 1}} = {{{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} + {\frac{\gamma_{T}\left( \phi_{e} \right)}{\gamma_{T}\left( \phi_{o} \right)}{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} - \frac{T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{o} \right)} + {l_{c\; 1}\left( {\omega_{c\; 1} - {\hat{\omega}}_{c\; 1}} \right)}}} & \left\lbrack {{Formula}\mspace{14mu} 5} \right\rbrack\end{matrix}$

where,

ω_(c1): Measured clutch angular velocity of first clutch

l_(c1): Observer feedback gain for clutch angular velocity of firstclutch

ω_(c1)−{circumflex over (ω)}_(c1): Clutch angular velocity error offirst clutch.

Under the theoretical assumption that a difference between the firstclutch model and the actual first clutch dynamics has been reflected toa difference between the actually measured clutch angular velocity ofthe first clutch and the estimated clutch angular velocity determinedfrom the first clutch model, correction which is performed by feedingback the clutch angular velocity error of the first clutch to the firstclutch model by the controller is based on that when the difference isrepeatedly multiplied by an appropriate observer feedback gain, thedifference gradually decreases and the first clutch model will be closerto the first clutch dynamics.

The second clutch model may be expressed as the following Formula 6.

$\begin{matrix}{{J_{c\; 2}^{\prime}{\overset{\overset{\cdot}{\hat{}}}{\omega}}_{c\; 2}} = {{{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} + {\frac{\gamma_{T}\left( \phi_{o} \right)}{\gamma_{T}\left( \phi_{e} \right)}{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} - \frac{T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{e} \right)}}} & \left\lbrack {{Formula}\mspace{14mu} 6} \right\rbrack\end{matrix}$

where,

J′_(c2): Equivalent moment of inertia of second clutch

{circumflex over ({dot over (ω)})}_(c2): Estimated clutch angularacceleration of second clutch

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

T_(tc1): Target clutch torque of first clutch

{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

T_(tc2): Target clutch torque of second clutch

{circumflex over (μ)}_(c2)T_(tc2): Clutch torque of second clutch

φ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . )

φ_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . )

γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e)

γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o)

{circumflex over (ω)}_(w): Estimated wheel angular velocity

T_(se)({circumflex over (ω)}_(c2),{circumflex over (ω)}_(w)): Torsionaltorque of driveshaft when even-numbered gear stage is engaged

${T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}}$

k_(s): Stiffness coefficient of driveshaft

b_(s): Damping coefficient of driveshaft

{circumflex over (ω)}_(c2): Estimated clutch angular velocity of secondclutch.

Real-time correction by feeding back the clutch angular velocity errorof the second clutch to the second clutch model may be expressed as thefollowing Formula 7.

$\begin{matrix}{{J_{c\; 2}^{\prime}{\overset{\overset{\cdot}{\hat{}}}{\omega}}_{c\; 2}} = {{{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} + {\frac{\gamma_{T}\left( \phi_{o} \right)}{\gamma_{T}\left( \phi_{e} \right)}{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} - \frac{T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{e} \right)} + {l_{c\; 2}\left( {\omega_{c\; 2} - {\hat{\omega}}_{c\; 2}} \right)}}} & \left\lbrack {{Formula}\mspace{14mu} 7} \right\rbrack\end{matrix}$

where,

ω_(c2): Measured clutch angular velocity of second clutch

l_(c2): Observer feedback gain for angular velocity of second clutch

ω_(c2)−{circumflex over (ω)}_(c2): Clutch angular velocity error ofsecond clutch

Under the theoretical assumption that a difference between the secondclutch model and the actual second clutch dynamics has been reflected toa difference between the actually measured clutch angular velocity ofthe second clutch and the estimated clutch angular velocity determinedfrom the second clutch model, correction which is performed by feedingback the clutch angular velocity error of the second clutch to thesecond clutch model by the controller is based on that when thedifference is repeatedly multiplied by an appropriate observer feedbackgain, the difference gradually decreases and the second clutch modelwill be closer to the second clutch dynamics.

The clutch friction force characteristic model of the first clutch maybe expressed as the following Formula 8.

{circumflex over (μ)}_(c1)({circumflex over (ω)}_(s1),{circumflex over(z)}_(c1))=σ_(c10) {circumflex over (z)} _(c1)+σ_(c11){circumflex over(ż)}_(c1)+σ_(c12){circumflex over (ω)}_(s1), where

{circumflex over (ω)}_(s1)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c1)

${\overset{\overset{\cdot}{\hat{}}}{z}}_{c\; 1} = {{\hat{\omega}}_{s\; 1} - {\sigma_{c\; 10}\frac{{\hat{\omega}}_{s\; 1}}{g\left( {\hat{\omega}}_{s\; 1} \right)}{\hat{z}}_{c\; 1}}}$

{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch

{circumflex over (ω)}_(s1): Estimated clutch slip of first clutch

{circumflex over (ω)}_(e): Estimated engine angular velocity

{circumflex over (ω)}_(c1): Estimated clutch angular velocity of firstclutch

σ_(c10): Stiffness coefficient against internal friction force of firstclutch

σ_(c11): Damping coefficient against internal friction force of firstclutch

σ_(c12): Damping coefficient for slip of first clutch

z_(c1): Internal variable for determining friction force of first clutch

g({circumflex over (ω)}_(s1)): z_(c1) Friction force according to slipof first clutch when a change of z_(c1) is 0 (normal state)

g({circumflex over (ω)}_(s1))=f _(c1c)+(f _(c1s) −f _(c1c))e^(−({circumflex over (ω)}) ^(s1) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²

f_(c1c): Coefficient of kinetic friction of first clutch

f_(c1s): Coefficient of static friction of first clutch

ω_(cs): Critical slip velocity (threshold velocity for discriminatingstatic friction and kinetic friction).

The clutch friction force characteristic model of the second clutch maybe expressed as the following Formula 9.

{circumflex over (μ)}_(c2)({circumflex over (ω)}_(s2),{circumflex over(z)}_(c2))=σ_(c20) {circumflex over (z)} _(c2)+σ_(c21){circumflex over(ż)}_(c1)+σ_(c22){circumflex over (ω)}_(s2), where

{circumflex over (ω)}_(s2)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c2)  [Formula 9]

${\overset{\overset{\cdot}{\hat{}}}{z}}_{c\; 2} = {{\hat{\omega}}_{s\; 2} - {\sigma_{c\; 20}\frac{{\hat{\omega}}_{s\; 2}}{g\left( {\hat{\omega}}_{s\; 2} \right)}{\hat{z}}_{c\; 2}}}$

{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch

{circumflex over (ω)}_(s2): Estimated clutch slip of second clutch

{circumflex over (ω)}_(e): Estimated engine angular velocity

ω_(c2): Estimated clutch angular velocity of second clutch

σ_(c20): Stiffness coefficient against internal friction force of secondclutch

σ_(c21): Damping coefficient against internal friction force of secondclutch

σ_(c22): Damping coefficient for slip of second clutch

z_(c2): Internal variable for determining friction force of secondclutch

g({circumflex over (ω)}_(s2)): z_(c2) Friction force according to slipof second clutch when a change of z_(c2) is 0 (normal state)

g({circumflex over (ω)}_(s2))=f _(c2c)+(f _(c2s) −f _(c2c))e^(−({circumflex over (ω)}) ^(s2) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²

f_(c2c): Coefficient of kinetic friction of second clutch

f_(c2s): Coefficient of static friction of second clutch

ω_(cs): Critical slip velocity (threshold velocity for discriminatingstatic friction and kinetic friction).

The clutch characteristic variable {circumflex over (μ)}_(c1) of thefirst clutch and the clutch characteristic variable {circumflex over(μ)}_(c2) of the second clutch that are obtained, as described above,have the characteristics shown in FIG. 3. For reference, μ=μ_(c1)=μ_(c2)in FIG. 3.

That is, μ=1 means that a clutch has been engaged by a target, so thatthe target clutch torque input by the controller and the clutch torqueestimated from the powertrain model are the same, μ<1 meansunder-engaging in which a clutch has not been engaged less than atarget, and μ>1 means over-engaging in which a clutch has been engagedmore than a target.

For reference, the clutch friction force characteristic models of thefirst clutch and the second clutch refer to a reference document (C.Canudas de Wit, H. Olsson, K. J. Astrom, P. Lischinsky, “A new model forcontrol of systems with friction”, IEEE Transaction on AutomaticControl, Vol. 40, No. 3, 1995).

The vehicle model may be expressed as the following Formula 10.

J _(v){circumflex over ({dot over (ω)})}_(w) =T _(sn)({circumflex over(ω)}_(ci),{circumflex over (ω)}_(w))−T _(L)({circumflex over (ω)}_(w)),where  [Formula 10]

J_(v): Equivalent moment of inertia of vehicle

{circumflex over ({dot over (ω)})}_(w): Estimated wheel angularacceleration

T_(sn)({circumflex over (ω)}_(ci),{circumflex over (ω)}_(w)):T_(so)({circumflex over (ω)}_(c1),{circumflex over (ω)}_(w)) when anodd-numbered gear stage is engaged, T_(se)({circumflex over(ω)}_(c2),{circumflex over (ω)}_(w)) when an even-numbered gear stage isengaged

n=o or e, i=1 or 2

T_(L)({circumflex over (ω)}_(w)): Vehicle load

{circumflex over (ω)}_(w): Estimated wheel angular velocity.

Real-time correction by feeding back the wheel angular velocity error ofa vehicle to the vehicle model may be expressed as the following Formula11.

J _(v){circumflex over ({dot over (ω)})}_(w) =T _(sn)({circumflex over(ω)}_(ci),{circumflex over (ω)}_(w))−T _(L)({circumflex over (ω)}_(w))+l_(w)(ω_(w)−{circumflex over (ω)}_(w)), where  [Formula 11]

ω_(w): Estimated wheel angular velocity

l_(w): Observer feedback gain for vehicle wheel angular velocity error

The vehicle load T_(L) may be determined by the following Formula 12.

T _(L)({circumflex over (ω)}_(w))=r _(w)(K _(r) M _(v) g cos θ_(r)−½ρC_(d) A _(F) r _(w) ²{circumflex over (ω)}_(w) ² −M _(v) g sinθ_(r))  [Formula 12]

where,

r_(w): dynamic rolling radius of vehicle wheel

K_(r): Rolling resistance coefficient

M_(v): Mass of vehicle

g: Acceleration of gravity

θ_(r): Gradient of road

ρ: Air density

C_(d): Drag coefficient

A_(F): Frontal area of vehicle.

For reference, the shifting information which is input to the powertrainmodel by the controller is used for the first clutch model, the secondclutch model, and the vehicle model, as described above.

In the step in which the controller estimates the clutch torque of thefirst clutch and the clutch torque of the second clutch by determiningthe powertrain model, it is possible to estimate the clutch torque ofthe first clutch and the clutch torque of the second clutch bydetermining the engine model, the first clutch model, the second clutchmodel, and the vehicle model using numerical integration etc.

According to an exemplary embodiment of the present invention describedabove, when the engine of a vehicle starts and the controller that isconfigured to control the DCT starts to operate, an initial value isimmediately set, the clutch torque of the first clutch and the secondclutch described above is estimated, and is used to control the firstclutch and the second clutch, for example, through comparison withtarget clutch torque which is determined by a T-S curve map. The presentoperation is repeated until the controller stops operating due tostopping of the vehicle or the engine.

The initial value may be set as measurement values of various sensors, aT-S curve map, information from an EMS, etc.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper”, “lower”, “inner”, “outer”, “up”, “down”,“upwards”, “downwards”, “front”, “rear”, “back”, “inside”, “outside”,“inwardly”, “outwardly”, “internal”, “external”, “inner”, “outer”,“forwards”, and “backwards” are used to describe features of theexemplary embodiments with reference to the positions of such featuresas displayed in the figures. It will be further understood that the term“connect” or its derivatives refer both to direct and indirectconnection.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit thepresent invention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described toexplain certain principles of the present invention and their practicalapplication, to enable others skilled in the art to make and utilizevarious exemplary embodiments of the present invention, as well asvarious alternatives and modifications thereof. It is intended that thescope of the present invention be defined by the Claims appended heretoand their equivalents.

What is claimed is:
 1. A clutch torque estimating method for atransmission of a vehicle, the clutch torque estimating methodcomprising: inputting model engine torque to a powertrain model by acontroller; inputting target clutch torque of a first clutch and targetclutch torque of a second clutch to the powertrain model by thecontroller; inputting shifting information related to the vehicle to thepowertrain model by the controller; correcting the powertrain model inreal time by feeding back an engine angular velocity error which is adifference between a measured engine angular velocity and an estimatedengine angular velocity determined from the powertrain model, a clutchangular velocity error of the first clutch which is a difference betweena measured clutch angular velocity of the first clutch and an estimatedclutch angular velocity of the first clutch determined from thepowertrain model, a clutch angular velocity error of the second clutchwhich is a difference between a measured clutch angular velocity of thesecond clutch and an estimated clutch angular velocity of the secondclutch determined from the powertrain model, and a wheel angularvelocity error which is a difference between a measured wheel angularvelocity and an estimated wheel angular velocity determined from thepowertrain model, to the powertrain model by the controller; estimatingclutch torque of the first clutch and clutch torque of the second clutchby determining the powertrain model by the controller; and controllingthe first clutch and the second clutch using the estimated clutch torqueof the first clutch and the estimated clutch torque of the second clutchby the controller.
 2. The clutch torque estimating method of claim 1,wherein the powertrain model includes: an engine model determinedaccording to engine dynamics; a first clutch model and a second clutchmodel determined according to clutch dynamics; and a vehicle modeldetermined according to vehicle dynamics.
 3. The clutch torqueestimating method of claim 2, wherein the model engine torque isconfigured to be input to the powertrain model with an estimated enginetorque error determined by cumulative-integrating the engine angularvelocity error.
 4. The clutch torque estimating method of claim 3,wherein the target clutch torque of the first clutch is multiplied by aclutch characteristic variable of the first clutch determined by aclutch friction force characteristic model of the first clutch and isthen input to the powertrain model, and wherein the target clutch torqueof the second clutch is multiplied by a clutch characteristic variableof the second clutch determined by a clutch friction forcecharacteristic model of the second clutch and is then input to thepowertrain model.
 5. The clutch torque estimating method of claim 4,wherein the engine model isJ _(e){circumflex over ({dot over (ω)})}_(e) =T _(e0)+{circumflex over(δ)}_(e)−{circumflex over (μ)}_(c1) T _(tc1)−{circumflex over (μ)}_(c2)T _(tc2), where J_(e): Engine moment of inertia {circumflex over ({dotover (ω)})}_(e): Estimated engine angular acceleration T_(e0): Modelengine torque {circumflex over (δ)}_(e): Estimated engine torque error{circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch T_(tc1): Target clutch torque of first clutch {circumflex over(μ)}_(c1)T_(tc1): Clutch torque of first clutch {circumflex over(μ)}_(c2): Clutch characteristic variable of second clutch T_(tc2):Target clutch torque of second clutch {circumflex over (μ)}_(c2)T_(tc2):Clutch torque of second clutch.
 6. The clutch torque estimating methodof claim 4, wherein the first clutch model is${{J_{c\; 1}^{\prime}{\overset{\overset{\cdot}{\hat{}}}{\omega}}_{c\; 1}} = {{{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} + {\frac{\gamma_{T}\left( \phi_{e} \right)}{\gamma_{T}\left( \phi_{o} \right)}{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} - \frac{T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{o} \right)}}},$where J′_(c1): Equivalent moment of inertia of first clutch {circumflexover ({dot over (ω)})}_(c1): Estimated clutch angular acceleration offirst clutch {circumflex over (μ)}_(c1): Clutch characteristic variableof first clutch T_(tc1): Target clutch torque of first clutch{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch T_(tc2): Target clutch torque of second clutch {circumflex over(μ)}_(c2)T_(tc2): Clutch torque of second clutch φ_(e): Even-numberedgear stage (ex, 2-gear stage, 4-gear stage, 6-gear stage . . . ) φ_(o):Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gear stage .. . ) γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e) γ_(T)(φ_(o)): Gearratio at gear stage φ_(o) {circumflex over (ω)}_(w): Estimated wheelangular velocity T_(so)({circumflex over (ω)}_(c1),{circumflex over(ω)}_(w)): Torsional torque of driveshaft when odd-numbered gear stageis engaged${T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}}$k_(s): Stiffness coefficient of driveshaft b_(s): Damping coefficient ofdriveshaft {circumflex over (ω)}_(c1): Estimated clutch angular velocityof first clutch.
 7. The clutch torque estimating method of claim 4,wherein the second clutch model is${{J_{c\; 2}^{\prime}{\overset{\overset{\cdot}{\hat{}}}{\omega}}_{c\; 2}} = {{{\hat{\mu}}_{c\; 2}T_{{tc}\; 2}} + {\frac{\gamma_{T}\left( \phi_{o} \right)}{\gamma_{T}\left( \phi_{e} \right)}{\hat{\mu}}_{c\; 1}T_{{tc}\; 1}} - \frac{T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)}{\gamma_{T}\left( \phi_{e} \right)}}},$where J′_(c2): Equivalent moment of inertia of second clutch {circumflexover ({dot over (ω)})}_(c2): Estimated clutch angular acceleration ofsecond clutch {circumflex over (μ)}_(c1): Clutch characteristic variableof first clutch T_(tc1): Target clutch torque of first clutch{circumflex over (μ)}_(c1)T_(tc1): Clutch torque of first clutch{circumflex over (μ)}_(c2): Clutch characteristic variable of secondclutch T_(tc2): Target clutch torque of second clutch {circumflex over(μ)}_(c2)T_(tc2): Clutch torque of second clutch φ_(e): Even-numberedgear stage (ex, 2-gear stage, 4-gear stage, 6-gear stage . . . ) φ_(o):Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gear stage .. . ) γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e) δ_(T)(φ_(o)): Gearratio at gear stage φ_(o) {circumflex over (ω)}_(w): Estimated wheelangular velocity T_(se)({circumflex over (ω)}_(c2),{circumflex over(ω)}_(w)): Torsional torque of driveshaft when even-numbered gear stageis engaged${T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}}$k_(z): Stiffness coefficient of driveshaft b_(s): Damping coefficient ofdriveshaft {circumflex over (ω)}_(c2): Estimated clutch angular velocityof second clutch.
 8. The clutch torque estimating method of claim 4,wherein the vehicle model isJ _(v){circumflex over ({dot over (ω)})}_(w) −T _(sn)({circumflex over(ω)}_(ci),{circumflex over (ω)}_(w))−T _(L)({circumflex over (ω)}_(w)),where J_(v): Equivalent moment of inertia of vehicle {circumflex over({dot over (ω)})}_(w): Estimated wheel angular accelerationT_(sn)({circumflex over (ω)}_(ci),{circumflex over (ω)}_(w)):T_(so)({circumflex over (ω)}_(c1),{circumflex over (ω)}_(w)) when anodd-numbered gear stage is engaged, T_(se)({circumflex over(ω)}_(c2),{circumflex over (ω)}_(w)) when an even-numbered gear stage isengaged n=o or e, i=1 or 2${T_{so}\left( {{\hat{\omega}}_{c\; 1},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 1}}{\gamma_{T}\left( \phi_{o} \right)} - {\hat{\omega}}_{w}} \right)}}$T_(so): Torsional torque of driveshaft when odd-numbered gear stage isengaged {circumflex over (ω)}_(c1): Estimated clutch angular velocity offirst clutch {circumflex over (ω)}_(w): Estimated wheel angular velocityk_(s): Stiffness coefficient of driveshaft b_(s): Damping coefficient ofdriveshaft ω_(c1): Measured clutch angular velocity of first clutchφ_(o): Odd-numbered gear stage (ex, 1-gear stage, 3-gear stage, 5-gearstage . . . ) γ_(T)(φ_(o)): Gear ratio at gear stage φ_(o)${T_{se}\left( {{\hat{\omega}}_{c\; 2},{\hat{\omega}}_{w}} \right)} = {{\int_{0}^{t}{{k_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}d\; \tau}} - {b_{s}\left( {\frac{{\hat{\omega}}_{c\; 2}}{\gamma_{T}\left( \phi_{e} \right)} - {\hat{\omega}}_{w}} \right)}}$T_(se): Torsional torque of driveshaft when even-numbered gear stage isengaged {circumflex over (ω)}_(c2): Estimated clutch angular velocity ofsecond clutch ω_(c2): Measured clutch angular velocity of second clutchφ_(e): Even-numbered gear stage (ex, 2-gear stage, 4-gear stage, 6-gearstage . . . ) γ_(T)(φ_(e)): Gear ratio at gear stage φ_(e)T_(L)({circumflex over (ω)}_(w)): Vehicle load.
 9. The clutch torqueestimating method of claim 4, wherein the clutch friction forcecharacteristic model of the first clutch is{circumflex over (μ)}_(c1)({circumflex over (ω)}_(s1),{circumflex over(z)}_(c1))=σ_(c10) {circumflex over (z)} _(c1)+σ_(c11){circumflex over(ż)}_(c1)+σ_(c12){circumflex over (ω)}_(s1), where{circumflex over (ω)}_(s1)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c1)${\overset{\overset{\cdot}{\hat{}}}{z}}_{c\; 1} = {{\hat{\omega}}_{s\; 1} - {\sigma_{c\; 10}\frac{{\hat{\omega}}_{s\; 1}}{g\left( {\hat{\omega}}_{s\; 1} \right)}{\hat{z}}_{c\; 1}}}${circumflex over (μ)}_(c1): Clutch characteristic variable of firstclutch {circumflex over (ω)}_(s1): Estimated clutch slip of first clutch{circumflex over (ω)}_(e): Estimated engine angular velocity {circumflexover (ω)}_(c1): Estimated clutch angular velocity of first clutchσ_(c10): Stiffness coefficient against internal friction force of firstclutch σ_(c11): Damping coefficient against internal friction force offirst clutch σ_(c12): Damping coefficient for slip of first clutchz_(c1): Internal variable for determining friction force of first clutchg({circumflex over (ω)}_(s1)): Friction force according to slip of firstclutch when a change of z_(c1) is 0 (normal state)g({circumflex over (ω)}_(s1))=f _(c1c)+(f _(c1s) −f _(c1c))e^(−({circumflex over (ω)}) ^(s1) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²f_(c1c): Coefficient of kinetic friction of first clutch f_(c1s):Coefficient of static friction of first clutch ω_(cs): Critical slipvelocity (threshold velocity for discriminating static friction andkinetic friction).
 10. The clutch torque estimating method of claim 4,wherein the clutch friction force characteristic model of the secondclutch is{circumflex over (μ)}_(c2)({circumflex over (ω)}_(s2),{circumflex over(z)}_(c2))=σ_(c20) {circumflex over (z)} _(c2)+σ_(c21){circumflex over(ż)}_(c1)+σ_(c22){circumflex over (ω)}_(s2), where{circumflex over (ω)}_(s2)={circumflex over (ω)}_(e)−{circumflex over(ω)}_(c2)${\overset{\overset{\cdot}{\hat{}}}{z}}_{c\; 2} = {{\hat{\omega}}_{s\; 2} - {\sigma_{c\; 20}\frac{{\hat{\omega}}_{s\; 2}}{g\left( {\hat{\omega}}_{s\; 2} \right)}{\hat{z}}_{c\; 2}}}${circumflex over (μ)}_(c2): Clutch characteristic variable of firstclutch {circumflex over (ω)}_(s2): Estimated clutch slip of first clutch{circumflex over (ω)}_(e): Estimated engine angular velocity {circumflexover (ω)}_(c2): Estimated clutch angular velocity of first clutchσ_(c20): Stiffness coefficient against internal friction force of firstclutch σ_(c21): Damping coefficient against internal friction force offirst clutch σ_(c22): Damping coefficient for slip of first clutchz_(c2): Internal variable for determining friction force of first clutchg({circumflex over (ω)}_(s2)): Friction force according to slip of firstclutch when a change of z_(c2) is 0 (normal state)g({circumflex over (ω)}_(s2))=f _(c2c)+(f _(c2s) −f _(c2c))e^(−({circumflex over (ω)}) ^(s2) ^(/{circumflex over (ω)}) ^(cs) ⁾ ²f_(c2c): Coefficient of kinetic friction of first clutch f_(c2s):Coefficient of static friction of first clutch ω_(cs): Critical slipvelocity (threshold velocity for discriminating static friction andkinetic friction).